On Aug. 6, 1945, about 140,000 people were killed by an American atomic bomb that hastened the end of World War II. Another blast in Nagasaki three days later killed 70,000 more. Read the full story.

Yasuyoshi Chiba / AFP - Getty Images

Paper lantern floats are released into the water during a ceremony for the victims of the atomic bomb in Hiroshima at Ibirapuera park in Sao Paulo, Brazil, on August 5, 2012. The ceremony was synchronized at the same time as 8:15 am Japanese time - the hour that the bomb exploded over Hiroshima 67 years ago. According to the Brazil Hibakusha Association for Peace, 115 victims are said to live in Brazil.

A peaceful gathering in Hiroshima, Japan, as the city commemorates the 67th anniversary of the atomic bomb that was dropped there during World War II. NBCNews.com's Dara Brown reports.